Methods of Raising a Low Arterial Pressure. 383 



Table I. 



Blood pressure. 



Viscosity relative 

 to water. 



Relative blood 

 pressure. 



Relative viscosity. 



136 



3-0 



' 100 



100 



128 



2-65 



94 



89 



104 



2-3 



77 



77 



82 



2 -0 



60 



66 



It is evident that the diminution of viscosity is a sufficient explanation of 

 the inefficiency of saline solutions, so far as the immediate effect is concerned. 

 If, therefore, the viscosity of Kinger's solution could be raised by the addition 

 of some innocuous substance, a much better result would be obtained. 

 There are several substances which might be used for this purpose. 



Soluble starch has the disadvantage of not having sufficient viscosity, 

 •except in concentrated solutions. It does not give very homogeneous 

 solutions, and alters by keeping, even in the cold. The solution becomes 

 acid, as shown by Wolff and Fernbach (3), by separation of phosphoric acid, 

 so that neutralisation is necessary each time that it is used. It has, further, 

 the objection of a very small osmotic pressure. The importance of this fact 

 will be seen presently. 



Amylopectin, prepared by precipitation of ordinary starch with acetone, in 

 "the manner of Wolff and Fernbach, has a high viscosity, but an insignificant 

 osmotic pressure. 



Agar requires too high a temperature to melt the jelly, and is practically 

 devoid of osmotic pressure. 



Gum acacia in 7-per-cent. solution has a viscosity about equal to that of 

 blood. The commercial samples consist partly of the calcium salt. I find 

 that the one used in my experiments had a calcium content equal to 

 2'23 per cent, of calcium chloride. A 7-per-cent. solution would therefore 

 contain 016 per cent. This is too high for a normal physiological solution. 

 It is advisable to precipitate by the addition of the necessary amount of 

 phosphoric acid ; 7 grm. of the gum referred to require 9 - 38 c.c. of decimolar 

 phosphoric acid. On making just alkaline to neutral red with sodium 

 hydroxide, the calcium phosphate is precipitated and falls on standing. 

 The solution consists now of the sodium salt of the gum acid, saturated 

 with calcium phosphate. A saturated solution of calcium phosphate was 

 found by Einger to contain the optimal concentration of calcium. The 

 sodium salt has the further advantage of a slightly higher viscosity than the 

 calcium salt. To complete the solution, the correct amount of potassium 



